One of the most popular topics on our roastery tours is choosing the right filter bag: should you get a white or brown filter bag?
The correct answer is a white bag.
The reason for this is that white filter paper does not have any extra flavors. In other words, coffee filtered through bleached paper will not have much of an off-flavor from the filter bag itself, while a brown, or unbleached, filter bag is practically like wet cardboard in both smell and taste.
So what is the difference? Here we go a little deeper into the world of paper production and cellulose boilers, welcome to the journey!
Bleached filter paper does not contain wood glues, brown does.
In a paper mill, wood is used to make cellulose pulp, which is then used to make various types of paper. Wood consists of cellulose, hemicellulose, adhesives and other substances. As their name suggests, adhesives, or lignins, hold wood together.
So it's a question of whether the flavor produced by the filter paper is affected by the wood binders or not. As you can tell from the opening text, bleached paper does not have these wood binders affecting the flavor, while unbleached paper does have the binders bringing their own, erm, aroma.
Oxygen-bleached filter paper is made in the same way as other white paper. At paper mills, the material in the pulp boiler is bleached with oxygen and various bleaching agents (although not with chlorine, chlorine bleaching was banned in 2007), after which filter paper is pressed from the cellulose pulp. This creates bleached sterile filter paper that is free of adhesives or other wood flavors.
Brown, or unbleached, filter paper is made from the same material as cardboard and brown paperboard. When the cellulose pulp is not bleached, the wood glues, or lignins, remain in the mixture. They give the coffee an unpleasant taste, especially when you filter coffee that is practically boiling through such brown paper.
As a side note, the term "oxygen bleached" filter paper, often used in coffee circles, is a bit inaccurate, as oxygen bleaching alone turns the paper light brown. Other parts of the bleaching process brighten the color to white.
Why is brown filter paper even made?
Why do brown filter bags even exist, you ask. We at the roastery don't fully understand it ourselves, we answer. It's probably for historical reasons and a sense of ecology.
When researching this topic, we had to look for answers from older people, because apparently, back in the 1900s, only bleached filter papers were available in stores. Brown bags came to offer a more ecological alternative, and in the past, bleaching used heavy chemicals.
Nowadays, production methods are a bit lighter. Brown filter paper itself has also been carefully cleaned and designed for food contact, so there is no need to give up its use for health reasons.
But if you want to fully enjoy hand-picked, high-quality coffee, you shouldn't use almost boiling water to extract the wood glues from the coffee liquid, but rather let the water and ground coffee extract through clean, neutral, or white filter paper!
Moccamaster white filter papers are available for sale in our online store.